Preparation of thermoset cycloolefin polymers via metathesis catalysts is a relatively recent development in the polymer art. Klosiewicz, in U.S. Pat. Nos. 4,400,340, 4,568,660, 4,469,809 and 4,436,858, and Tom in U.S. Pat. No. 4,507,453, teach preparation of such polymers from dicyclopentadiene (DCPD) and other similar cycloolefins via a two-stream reaction injection molding technique wherein a first stream, including the catalyst, and a second stream, including a catalyst activator, are combined in a mix head and immediately injected into a mold where, within a matter of seconds, polymerization and molding to a permanently fixed shape take place simultaneously. Such polymers can also be molded from a single stream with use of an additive to delay gelation. These polymers are characterized by high impact strength and high modulus. Characteristics of these and other thermoset polymers include insolubility in common solvents such as gasoline, naphtha, chlorinated hydrocarbons, and aromatics as well as resistance to flow at elevated temperatures. Although thermoset polymers are characterized by their insolubility, they are still subject to appreciable swelling in solvents as well as to degradation by acids. Also, despite thermoset polymers being insoluble in hydrocarbon solvents due to extensive crosslinking, if untreated, when immersed in such solvents for a prolonged period of time, they will sufficiently absorb such hydrocarbons to degrade the polymer's properties. Another feature of these polymers is that when polymerization of the DCPD monomer has been completed, there is often a small percentage of monomer remaining in the article which is slowly emitted over a period of time. It would be desirable to prevent the emission of monomer.
Surface treatments have been used on other polymers to obtain desired properties. Fluorination is used to seal polyethylene gasoline tanks and bottles that contain motor oil. This process uses fluorine diluted with an inert gas at an elevated temperature with a contact time of a few seconds. The basic process is disclosed in U.S. Pat. No. 3,758,450. A less effective process for making plastic fuel tanks involves sulfonation with sulfur trioxide followed by neutralization with ammonia. The presence of traces of moisture requires further sealing with an amino resin.
It is an objective of this invention to treat the surfaces of poly(DCPD) articles to increase their resistance to degradation by chemicals such as acids, hydrocarbons, and other materials. It is also an object of this invention to treat the surfaces of these articles to significantly reduce the escape of residual monomer remaining in the article after polymerization. A further object of this invention is to improve the adherence of paints to the surfaces of poly(DCPD) articles.